Look at two long-term best friends. Perhaps your own relationship with your best friend(s).
That, with living together and sex - change the sex of one of them if necessary.
Acceptance and understanding of each other's differences (not just "tolerance")
Example: It's Christmas/Thanksgiving/whatever. One wants to spend it with his/her parents, hasn't seen them for a long while. (S)he knows and understands that the other doesn't enjoy going to wherever his/her parents are. Says to other "I'm going to my parents this holiday. You're welcome to come if you wish but if you don't want to, you can do something else."
The other understands that it's been a long while since his/her partner has visited with parents and the desire/need to see them. (S)He does not have preconceptions of "we must
spend our holidays together." Opts to go fishing with his/her buddies instead.
After holidays, they get together refreshed having enjoyed themselves, have a lot to talk about and really appreciate: the time spent doing their own thing, the mutual respect and understanding that makes it possible, and the time they're spending together at this time after having not seen each other for a week or so.
That's based on a real couple I know.
If they're doing something together, it's because they decide to do something together at that time ("mutuality" - mutual decision to do this together at this time) - no obligations, no expectations, no "if you really loved me, you'd endure the 12-hour drive to my parent's place", no "we went to your parents' last year, you've got to come to mine, now, even though my dad gives you shit every five minutes", no conditions.
I like this, (s)he doesn't, I'll go and do this at this time, (s)he can enjoy what (s)he wants and we'll both enjoy doing something we both like later and it'll be really special.
Just as friends don't have to do everything together and give each other their own space then have a whale of a good time doing things together.
Things that affect both are discussed and worked out as equals. There will be times when compromises have to be made and not everyone gets what they want - not all of life is "well, you can do it your way and I'll do what I want", especially when it comes to shared accommodation, children etc.
They'll argue but then calm down and make up. They'll understand and respect each other's points of view.
edited 11th Apr '13 2:34:35 PM by Wolf1066